#define _CRT_SECURE_NO_WARNINGS

class Solution {
public:
    int peakIndexInMountainArray(vector<int>& arr) {
        int left = 0, right = arr.size() - 1;
        while (left < right)
        {
            int mid = (right - left) / 2 + left;
            if (arr[mid] > arr[mid + 1])
                right = mid;
            else
                left = mid + 1;
        }
        return left;
    }
};